#include <bits/stdc++.h>

using namespace std;
using ll = long long;
string s;
int main() {
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    cin >> s;
    sort(s.begin(), s.end());
    cout << s << endl;
    return 0;
}